Progress in microelectronics has been possible in a large part due to improvements in the microelectronics manufacturing technology. Unfortunately, continued advances in microelectronic manufacturing require substantial investments of capital and time to develop the increasingly complex technology. This increase in the cost of technology development threatens to slow the growth rate of electronic technology and the electronics industry.
Manufacturing of integrated circuits starts with a thin slice of ultra-pure silicon crystal, called a silicon wafer, and proceeds by a sequence of precisely controlled fabrication steps performed on the wafer. The specification of the sequence of steps, along with the precise operation to be performed at each step is known as a process flow. The task of designing a process flow to produce the desired electronic devices can be divided into two parts. The first part is to design process modules that can result in the desired set of changes in the wafer-state. This part is called module synthesis. The second part involves assembling the process modules into a process flow by selecting a sequence of modules and the exact wafer-state transformation performed by each module, such that the end of flow wafer-state results in the desired devices. This second part is called herein flow synthesis.